Year
2022
Degree Name
Doctor of Philosophy
Department
School of Civil, Mining and Environmental Engineering
Abstract
Underground excavations such as tunnels, ground slopes, unstable rock walls, and cliffs are some examples where rock bolts and cable bolts can be used to safeguard human life and equipment. Rock bolts and cable bolts (so-called tendons) are tension members that pull the loose parts of the ground together and anchor them to the nearest intact and stable ground. Reinforcement of sagging bedding layers and strata, supporting the immediate roof of a tunnel in a discontinuous rock, and stabilizing the rock slopes that have the potential to topple can be some of the routine applications of ground anchors. However, in practice, either tensile or shear, or the combination of both tensile and shear loads, might be applied to the tendons. The performance of the ground system is highly dependent on the ground conditions as well as installation properties. Thus, it is paramount to understand the exact loading conditions of tendons and propose a proper design for each application according to the requirements of each specific application.
A variety of analytical, experimental, and numerical research have been carried out to illustrate the failure mechanism of tendons under axial and shear loads. Axial loading capacity and failure modes of tendons are examined by in-field or laboratory pullout tests. Laboratory single-shear or double-shear tests also aim to characterise the behaviour of tendons under shear loading conditions. Angled shear tests are for cases where both axial and shear loads are applied simultaneously. While the number of studies on axial loading is significantly high, studies on angled and pure shear are limited. This stems from the fact that shear studies can be merely undertaken in the laboratory and require special powerful testing facilities, while pullout tests can be done both in the field and in the laboratory.
Although most ground anchors are designed for long-term loading conditions such as gravitational settlement and deformation, local earthquakes such as blasting in mines, rockburst, coal burst, and global earthquakes apply significantly high dynamic load to the tendons in very short periods of time. Hence, attention must be paid to the charachterisation of the tendons' behaviour under dynamic loading as well as static loading. Field measurements of the dynamic load applied on tendons, the development of mathematical and numerical models, and laboratory tests are some of the study methods for dynamic loading conditions. Various laboratory technologies have been developed for dynamic pullout testing of the tendon in the laboratory. This is while dynamic shear loading tests are not as common as axial loading. This even becomes less common with dynamic shear testing of tendons at angles. Besides, a comparative study of both static and dynamic loading in axial and shear loading conditions there was little else be seen in the literature review of this topic. It is also worth mentioning that the technology of tendons has developed and is yet to develop according to the needs of the industry. The number of studies on rock bolts is considerably larger as it is a common reinforcement system among both civil and mining engineers. This is while studies on cable bolts are relatively limited. Therefore, continuous research and examination of new tendons are inevitable.
This thesis aims to investigate different possible loading conditions applied to cable bolts. To this, two different cable bolts (15.2 mm seven-wire and 63 t nine-wire Sumo cable bolts) were subjected to different loading conditions, including static and dynamic perpendicular shear, static angled shear, and static and dynamic pullout tests.
Recommended Citation
Anzanpour, Sina, The Load Transfer Mechanism of Ground Tendons Subjected To Static and Dynamic Loading Conditions, Doctor of Philosophy thesis, School of Civil, Mining and Environmental Engineering, University of Wollongong, 2022. https://ro.uow.edu.au/theses1/1608
FoR codes (2008)
0905 CIVIL ENGINEERING
Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.